Treatment of asphalt to remove unsaturated compounds therefrom



Patented Dec. 31, 1935 v UNITED STATES TREATMENT OF ASPHALT TO UNSATURATED COMPOUNDS THERE- FROM George R. Hoover, Middletown, Ohio, assignor to The American Rolling Mill Company, Middletown, Ohio, a corporation of Ohio No Drawing. Application July 15, 1932,

Serial No. 622,828

3 Claims. '(Cl. 196-74) My invention relates to a process suitable for the treatment of asphaltic substances for prolonging the adhesive life thereof, especially in connection with the use of these substances in adherent condition to. metal articles such as culverts and the like. It is an object of my invention to provide a convenient and economical method of treating asphaltic materials which does not involve the provision of great amounts of apparatus, and which, for the most part, can be practiced with such apparatus as is currently employed in the treatment of such materials.

Somewhat more specific objects of my invention may be thought of (as applied to asphalt and analogous compounds) as the provision of a method for treating these materials in such a way as to prevent their deterioration under the action of air, moisture, light and weather conditions, particularly in respect to the adhesive duality thereof.

These and other objects of my invention which will be set forth hereinafter or W111 be apparent to one skilled in the art upon reading these specifications, I accomplish by that certain series of process steps of which I shall now describe an exemplary embodiment.

It has been found, for example, that with asphalts possessing good adhesive qualities, application thereof maybe made to metallic surfaces with initially a strong bond, but that in the course of time the material appearsto deteriorate in such a waythat, while the body thereof may be satisfactory for many purposes, the nature of the bond between the asphaltic body and the metal is weakened. This is of importance not only in the use of asphaltic substances in the form of paints and cements for ordinaryprotec-.

tive work, but also in the manufacture of invert paved culverts in accordance with themethod of Cushman Patent Nos. 1,735,732 and 1,652,703, or by other methodsto produce analogous articles. The general object of such methods is to produce a corrugated culvert in which the invert or actual floor is covered with a paving which acts not only as a protective coating, but which also fills up the corrugations level full so as to do away with the eddy currents produced in the water flowing through the culvert, which eddy currents, it has been demonstrated, acting upon the abrasive material, pebbles and the like, entrained in the water, are responsible for wear on the corrugations at or adjacent the invert, such as rapidly attacks the galvanized coating and permits corrosion of the base metal. In a sense this eifect may be thought of as an aging of the and'by adding tothe air passing through the cumstances-of the blowing treatment.

asphaltic material, but my investigations have demonstrated that the adhesive life of an air blown asphalt of ,a given. melting point and manufactured from a given blend of asphaltic,v material, will be in inverse proportion to the 5 amount Of wax and grease compounds remain! ing in the asphalt at the end of the manufacturing process.

While the migration of wax or grease-like compounds appears to have something to do with the m adhesive life of a bitumen, theemphasis in my invention is placed upon the removal of such objectionablecompounds or their reduction to a minimum in the material at the end of the manufacturing operation. Briefly, in the practice of i5 my invention, I have discovered that the use of ous proposals have been made for treating asphalt to harden the same, but for other purposes, such,

for example, as the use of sulphur, and some of these'proposals appear to prolong the adhesive life of an asphaltic substance. Uniformly, however, they affect the other qualities-of the bitumen, and in many circumstancesrender it unfit for the use intended. Thus a treatment with sulphur 3 will produce a hard and brittle'asphalt having a 7 low penetration,as determined by the practices of the American Society for Testing Materials.

In the use of asphaltic compounds-for; culvert work, as hereinabove referred to, not only is a non-aging bitumen required, but also one of continuously high adhesive quality, non brittle and relatively continuously plastic in the sense of being deformable under strain. A hard and brittle material, even though it has long adhesive life, is not suitable.

I have found that by blowing asphalt wlth'alr by any of the general processes at present in use, 7

asphalt a quantitybf ammonia gas or some material which will liberate the free ammonia, I can secure a high degree of freedomfrom unsaturated hydrocarbon material, such as wax or grease-like compounds, while-securing the other results, as ascertained by the standard methods of making physicaltests upon asphalt, which would normally be expected from the naturelof the raw materials and the time duration-and cir- I will now give an example of an experimental treatment illustrating the practice of my invention. A standard or commercial blend of flux oil was selected and divided into various parts. The first proportion was treated by blowing in the usual manner, and resulted in an asphaltic material having the characteristics normally to be expected from such a treatment. The percentage of non-adhesives in the particular material so treated was found to be 6.87%. Another portion of the material was treated in exactly the same way, excepting that 2% of ammonia gas was added to the air in the blowing process. This resulted in an asphaltic material, the physical characteristics of which were substantially identical with the material first treated, as determined by the standard so-called melting point and penetration tests, but in which the non-adhesive content was reduced to 2.4%.

In the blowing of asphalts I have employed various percentages of ammonia, ranging from .05% to 10% or more, from which I have concluded that .05% of ammonia is sufficient to effect the removal of most of the non-adhesive components of commercial grades of asphaltic substances. The amounts of ammonia gas and air are calculated on the basis of volume.

Test specimens of galvanized iron coated with asphaltic substances from tests similar to the above have been observed by me with respect to ageing characteristics. Specimens coated with asphalt blown by the ordinary or commercial methods showed an initial adhesion time of 23 minutes by the method set forth in the co-pending application of Messrs. Hoover and Shafor, Serial No. 594,298, filed February 20, 1932. After six months of ageing the same asphalt, tested by the same means and method, showed an adhesion time of 3 minutes. As distinguished from such specimens, asphaltic materials produced in ac cordance with my process showed an initial adhesion time of 23 minutes, and after six months of ageing an adhesion time of 20 minutes.

It will .be understood that my method may be varied to suit different characters of bituminous substances, just as the time of blowing, the'temperature and the like may be varied for a like purpose. I have found in general that the addition of 2% of ammonia by volume to the air used in a .commercial blowing process for producing the desired physical qualities in a bituminous substance will be suflicient to remove therefrom so great a percentage of non-adhesive substances as will contribute many-fold to the adhesive life of the material.

Various modifications may be made in my process without departing from the spirit of my invention. In general, my process contemplates the treatment of hydro-carbon materials containing a proportion of unsaturated hydro-carbons with ammonia gas, or some substance which will readily give off free ammonia under the conditions of the particular treatment. The use of ammonia or ammonium compounds is conveniently combined with the use of such processes as blowing, or the like, which are designed in themselves to alter the characteristics of the material by oxidation, polymerization, dehydration and/or distillation. While the effects of my treatment do not appear to be dependent upon concurrent effects, such as those just mentioned and otherwise produced, yet it is a commercial advantage of this step in my treatment, that it may be combined with such other treatments to produce the effect which I desire without at the sametime greatly modifying, if at all, the effects of such other treatments.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent, is:

1. That process of treating asphalt to prolong the adhesive life thereof, which comprises blowing asphalt with air at elevated temperatures and simultaneously treating it with an effective amount of ammonia gas for the purpose set forth.

2. That process of treating asphalts to prolong the adhesive life thereof, which comprises blowing said asphalts while substantially liquid and at elevated temperatures to give them the desired physical characteristics as determined by the usual test, and during the blowing operation introducing into the oxidizing gas employed for 40 blowing, an amount of ammonia effective to the end set forth.

3. A process of treating asphalts to prolong the adhesive life thereof, which comprises blowing said asphalts with an oxidizing gas to give them 4 the desired physical characteristics as determined by the usual tests, and during the blowing operation, introducing into the gas employed for blowing a portion of ammonia ranging in amount from .05 to 10% by volume of the total gas used for 50 blowing.

' GEORGE R. HOOVER. 

